This application is a national stage of PCT/EP99/10033 filed Dec. 17, 1999 and is based upon German national application 199 01 026.9 of Jan. 13, 1999 under the International Convention.
The invention relates to a method of and to an apparatus for connecting the running out or trailing end of a web of material with the oncoming or leading end of the web of a new wound roll in the unwinding of material webs, especially of paper or cardboard webs.
In unwinding devices for wound rolls of webs of material, for example paper webs or cardboard webs, splicing devices are known which connect the end of the running out material web (trailing end) with the web beginning (leading end) of a new wound roll. In the unwinding of heavy paper rolls which are wound on continuous metal shafts (tambours) and which can have a web width of 8 m and greater and a weight in excess of 50 tons, the splicing usually requires the processing machine which is downstream of the unrolling device to be brought to standstill.
A method and an apparatus of the type described here is known from EP 0 462 157 B1 in which initially the running out web is separated from the rest roll (previously unrolled roll) and the end of the separated running out web is held while the rest roll is replaced by a new wound roll. At the starting end web of the new roll, an adhesive strip is applied which is pressed against the end of the running out web and thereby fastens the end of the new roll to the running out web.
In the known method and apparatus, a problem arises in that, with especially large and heavy wound rolls and large web widths, it is not possible to provide a reliable web connection with a web end that projects only to a limited extent. This has its origins in the fact that it is not possible to apply the adhesive strip to the starting end of the web of the new wound roll exactly parallel to the axis thereof. Furthermore, it is not possible to position the new wound roll peripherally with sufficient precision that the holding device can move the adhesive strip with precision against the web end. The imprecision in the application of the adhesive strip and/or in the positioning of the new wound roll means that the web end cannot end precisely at the adhesive strip. Rather a free nonbonded remainder of the web will project to create problems in the further processing of the wound roll, especially in a printing or transverse cutting machine.
The invention has as its object an improvement in the method and apparatus described at the outset such that a connection can be produced without a projecting, nonbonded remainder of the web or with only a minimum of projecting nonbonded web remaining.
According to the invention, the end of the running out web is connected with the starting end of the web by means of two adhesive strips which are provided over the width of the web. Before splicing, a first adhesive strip can be applied with precision at the edge of the starting end of the new wound roll and the second adhesive strip can be applied precisely at the edge of the trailing end of the running out web. Upon connection of the webs, the end of the running out web is thus adhered to the beginning of the new web and the new web is so bonded to the running out web. Since the two adhesive strips can each be precisely positioned, there is neither a projecting web end of the new web nor a projecting free end of the running out web.
Preferably the second web strip is applied to the web end at a location in the web travel direction behind the web strip at the beginning of the web by pressing it against the new wound roll in order to minimize the thickness in the splicing region.